Integrated circuits (ICs) typically include a plurality of semiconductor devices and interconnect wiring. Networks of metal interconnect wiring are often used to connect the semiconductor devices from the semiconductor portion of the substrate. Multiple levels of metal interconnect wiring above the semiconductor portion of the substrate are connected together to form a back-end-of-the-line (“BEOL”) interconnect structure. Within such a structure, metal lines run parallel to the substrate and conductive vias run perpendicular to the substrate. The conductive vias typically interconnect the different levels of the metal wiring levels.
Two developments in the last decade have contributed to increased performance of contemporary ICs. One such development is the use of copper as the interconnect metal of the BEOL interconnect structure. Copper is advantageous because it has a higher conductivity compared with the other traditionally used interconnect metals, such as, for example, aluminum (Al).
A second development is the employment within the BEOL interconnect structure of a low dielectric constant (low k) dielectric material as the interlevel dielectric (ILD) layer or layers. By “low k,” it is meant that the dielectric constant of a particular dielectric material is less than that of silicon dioxide. The low k dielectric alternatives may be non-porous, porous or a combination of porous and non-porous. When copper is used as the metal in the interconnect wiring layers, a dielectric barrier layer or “dielectric cap” is typically required between the copper features and the ILD to prevent copper from diffusing into certain types of ILD materials so as to prevent the copper from damaging the electrical properties of the dielectric. Unfortunately, even with the dielectric cap positioned over the copper lines, some electromigration or diffusion of the copper atoms at the interface between the dielectric cap and the copper lines in the direction of the flow of electrons can occur. A void or short circuit in the copper line can occur as a result of the electromigration, thereby causing the semiconductor device to fail.
Accordingly, it is desirable to provide methods for forming Cu diffusion barriers that inhibit electromigration of copper atoms along copper lines that are formed in semiconductor interconnect structures. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background of the invention.